• NiAu alloy NPs have been prepared from a Li-butyl fast reduction method and undergo a sequential physical transition from NiAu alloy Au@Ni core-shell NiO-Au contact aggregates to produce highly stablized CO oxidation catalysts. This work and our related Fuel Cell research is funded by the DOE, the ONR, Exxon-Mobil and the University of Maryland Energy Research Center.

High Symmetry Naked Metal Clusters

The use of Zintl ions (main group polyanions, such as Pb94- and Sb73-) to make bimetallic clusters and nanoparticles (NPs) have resulted in a new class of cluster materials with unprecedented structures and intriguing potential applications. Examples include the fully characterized M@Pb102- and M@Pb122- ions (Fig. 2a) where M = Ni, Pd, Pt, by X-ray analysis, DFT studies, 207Pb NMR and 195Pt NMR investigations as well as mass spectrometry studies (LDI and ESI). In addition, we showed that the empty and K+ ion-paired clusters Pb102- and Pb122- could exist without transition metal interstitials. We have also synthesized and fully characterized the coupled tin clusters Ni2@Sn174-, Pd2@Sn184- and Pt2@Sn174- through extensive NMR and X-ray studies. The Ni2@Sn174- and Pt2@Sn174- are isoelectronic but have markedly different structures (see Fig. 2b, 1c) and fluxional behavior. The Pt2@Sn174- has a fused capsule-like structure in which all Sn atoms are in fast exchange, even at -50 °C, and couple equally to both Pt atoms. We have prepared and structurally characterized new “intermetalloid” clusters containing polypnictide ions and group 10 transition metals. The new complexes include Ni5Sb174- (Fig. 2d) and Pd7As164-, which do not resemble traditional Zintl clusters nor do they adopt the structures of the intermetallic phases.